Is it possible to use another map or slice as a key in a map?

In Go, the key in a map can only be types that support the comparison operation (operator ==). This means that using a map or slice as a key is not allowed because they are not compared by value.

If you need to use a composite key, you can:

• Use a string or another primitive type that is formed from the values of a map or slice (for example, serialize to JSON or use concatenation).
• Define your own structure with comparable fields and use it as a key.

Example using a structure as a key:

package main

import "fmt"

type Key struct {
    ID   int
    Name string
}

func main() {
    m := make(map[Key]string)
    k := Key{ID: 1, Name: "test"}
    m[k] = "value"
    fmt.Println(m[k])
}

Thus, you cannot directly use a map or slice as a key, but you can work around this limitation using other approaches.